title: Purification of human interleukin 1.
abstract: Interleukin I (IL-1) is a lymphocyte stimulant released by human monocytes cultured for 18-24 hours in tissue culture medium containing 5% serum and the non-specific immunostimulant lipopolysaccharide (LPS). Human IL-1 is found in the conditioned medium in a low molecular weight (approximately 13,000) and a high molecular weight (approximately 85,000) form. The high MW activity may result from the formation of a complex between IL-1 and serum constituents. During the course of purification, the low MW IL-1 activity is often recovered in a high MW form. Hollow fiber diafiltration and membrane ultrafiltration has been found to rapidly separate low MW IL-1 from all measurable protein with a yield of 4% of the original activity. The IL-1 which converts to the high MW form during the purification is recoverable, 21% of the original activity, but contains small amounts of serum proteins. Isoelectric focusing (IEF) of the low MW IL-1 resulted in a very highly purified sample which was analyzed by polyacrylamide gel electrophoresis (PAGE). Utilizing a new staining procedure which detects less than 1 ng of protein per band, the IEF-purified IL-1 revealed trace quantities (less than 1 ng) of a slowly migrating protein similar to immunoglobulin and no other bands. There were no bands which corresponded with the known electrophoretic mobility of IL-1. Since the samples applied to the gel contained significant biological activity, this result implies that human IL-1 is biologically active in picogram quantities.
mesh_terms: D000818:Animals; D002460:Cell Line; D005260:Female; D006801:Humans; D007375:Interleukin-1; D007525:Isoelectric Focusing; D008213:Lymphocyte Activation / Q000187:drug effects; D008264:Macrophages; D051379:Mice; D008970:Molecular Weight; D009000:Monocytes / Q000276:immunology*; D011506:Proteins / Q000302:isolation & purification* / Q000494:pharmacology; D014462:Ultrafiltration
chemical_list: D007375:Interleukin-1; D011506:Proteins